Refined three-dimensional simulation of ribbed bar pull-out tests based on an enhanced peridynamic model

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Peridynamic (PD) theory can effectively model discontinuous problems, but it remains a challenging task for refined three-dimensional (3D) simulation of bond-slip behaviors in pull-out tests, particularly when the rib of rebar is considered. The mesh size of the model needs to be small enough (e.g., decimillimetre or 0.1 mm) to simulate various shapes of ribs. Therefore, the scale of the PD model is usually significantly large and the computational efficiency is low. This paper proposes an enhanced bond-based PD (BPD) model to perform a refined 3D simulation of bond-slip behaviors in the ribbed bar pull-out test. In order to reduce the computation scale and improve efficiency, a practical 3D coupled element is developed to couple the fine PD model and coarse finite element (FE) model, where the PD is used to model the regions in concrete and rebar that are close to the interface, while FE model is used to simulate the regions far away from the interface. A computational framework is developed for implicit and static analyses of the coupled PD-FE model. A parallel computing strategy is adopted to improve the computational efficiency, and enhanced concrete and steel BPD models are presented to accurately simulate the nonlinear behaviors and damage of concrete and ribbed rebars. The enhanced PD modeling approach is implemented in an open-source finite element software framework, OpenSees, and verified by a cantilever beam under uniaxial loading conditions and a pushover analysis of an RC column. Based on the enhanced PD, a refined 3D simulation of ribbed rebar pull-out tests is performed. The bond-slip behaviors are studied in detail, e.g., the crack propagation with different types of ribs, concrete strengths, and rebar properties. The enhanced PD modeling approach provides an effective tool for refined simulation of the complicated bond-slip behaviors in RC structures.